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Evaluation of solvent-mediated phase transformation of glycine using oleic acid: Morphology and characterization study

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Chinese Journal of Chemical Engineering 2018年第9期26卷 1829-1836页

作者： Sevgi Polat Perviz Sayan Department of Chemical Engineering Faculty of Engineering Marmara University

The polymorphic phase transformation of β-glycine to α-glycine was carried out both in the absence and presence of various concentrations of oleic acid used as additive at 25 °C in a water/ethanol medium. The effects of oleic acid and its concentration on phase transformation time were determined by continuously measuring the ultrasonic velocity. The crystals obtained by the completion of the phase transformation were characterized by XRD, SEM, and tg/dtg. The XRD and SEM results indicated that oleic acid significantly impacted phase transformation time and the morphological characteristics of the crystals. In addition to SEM analysis, detailed crystal shape analysis was performed and the circularity, elongation, and convexity parameters were determined quantitatively. tg/dtg analyses were performed to investigate thermal decomposition behavior and to calculate the activation energies based on different kinetic models such as FWO, KAS, Starink, and Tang kinetic models. With the addition of oleic acid to the medium, the calculated activation energy values increased from 89.63–90.63 to153.8–155.4 kJ·mol^(-1). The activation energy values showed that oleic acid was adsorbed on the crystal surface;this result was supported by FTIR, elemental, and Kjeldahl analyses.

关键词：阶段转变形态学 tg/dtg 用油学习评估溶剂运动模型

Controlled growth of transition metal dichalcogenide via ther-mogravimetric prediction of precursors vapor concentration

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Nano Research 2021年第8期14卷 2867-2874页

作者： Long Fang Shaohua Tao Zhenzhen Tian Kunwu Liu Xi Li Jiang Zhou Han Huang Jun He Xiaoming Yuan Hunan Key Laboratory of Super Micro-structure and Ultrafast Process School of Physics and ElectronicsCentral South UniversityChangsha 410083China School of Physics and Electronic Sciences Changsha University of Science and TechnologyChangsha 410004China School of Materials Science and Engineering Central South University Changsha 410083China

Transition metal dichalcogenide(TMD)alloys and heterostructures are attracting increasing attention thanks to their unique electronic,optical,and interfacial properties.However,the growth fundamental of TMD alloys and heterostructures during one-step growth is still beyond understanding.Here,thermogravimetric(tg/dtg)technology is introduced to predict the evolution of the precursor(MoO_(3)and WO_(3))concentration in the vapor during growth.We establish the correlation between precursor concentration and the corresponding growth behavior.tg/dtg predication suggests that tuning precursor temperature and powder ratio can alter their concentration in the vapor,well explaining the formation of Mo_(x)W_(1-x)Se_(2) alloy or MoSe_(2)-WSe_(2) heterostructure at different growth conditions.Based on the tg/dtg analysis,we further design and grow a complex MoSe_(2)-Mo_(x)W_(1-x)Se_(2)-WSe_(2) heterostructure and Mo_(x)W_(1-x)Se_(2) monolayer alloys,confirming the validity of tg/dtg prediction in TMD crystal synthesis.Thus,employing tg/dtg to predict the synthesis of two-dimensional materials is of importance to understand the TMD growth behavior and provide guidance to the desired TMD heterostructure formation for future photoelectric devices.

关键词： tg/dtg Mo_(x)W_(1-x)Se_(2)alloys MoSe_(2)-WSe_(2)lateral heterostructures precursor concentration

Non-isothermal kinetics of styrene-butadiene-styrene asphalt combustion

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Chinese Physics B 2013年第6期22卷 660-665页

作者：吴珂朱凯韩君王金昌黄志义梁培 Faculty of Engineering Zhejiang University Jiangsu Bao Li Asphalt Co.LTD College of Optical and Electronic Technology China Jiliang University

The combustion characteristics of styrene-butadiene-styrene （SBS） asphalt are studied by thermogravimetric analysis （tg/dtg） at four different heating rates. According to the saturates/aromatics/resins/asphaltenes （SARA） fractionation method, the combustion process of SBS asphalt can be divided by Gaussian peak fitting into three main stages： oil content release, resin pyrolysis, and asphaltene and char combustion. When the heating rate increases, the mass losses of the oil content and resin pyrolysis increase, and less asphaltenes are formed at a higher temperature. The activation energy values are calculated by the Coats-Redfern method to be in the range 61.6 kJ/mol-142.9 kJ/mol. The Popescu method is used for the kinetic analysis, and the result shows that the three stages of asphalt combustion can be explained by the sphere phase boundary reaction model, the second order chemical reaction model, nucleation, and its subsequent growth model, respectively.

关键词： SBS asphalt combustion non-isothermal kinetic tg/dtg

Effect of Hygrothermal Cycle Aging on the Mechanical Behavior of Single-lap Adhesive Bonded Joints

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Journal of Wuhan University of Technology(Materials Science) 2019年第2期34卷 337-344页

作者：范以撒那景新 MU Wenlong QIN Guofeng TAN Wei School of Mechanical Engineering North China University of Water Resources and Electric Power State Key Laboratory of Automotive Simulation and Control Jilin University

The aging behavior of single lap joints(SLJ) in hygrothermal cycles was investigated and compared by using a shearing strength test, Fourier transform infrared spectroscopy(FTIR), thermogravimetric analysis(tg/dtg), energy dispersive spectrometry(EDS) and scanning electronic microscopy(SEM). The temperature/relative humidity was set at 80 ℃/95% and –40 ℃/30% for 20 cycles, 40 cycles, and 60 cycles(one cycle was 12 hours), respectively. The experimental results show that hygrothermal aging significantly decreases the failure strength of adhesive joints. However, the failure displacement increases as the number of aging cycles increases. In addition, hygrothermal aging changes the failure mode of the adhesive joints from a cohesive fracture in un-aged adhesive layers to an interfacial failure of aged adhesive joints.

关键词： single lap joints hygrothermal aging mechanical behavior FTIR tg/dtg EDS

Thermal Decomposition Behavior of Terephthalate in Inert Gas

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China Petroleum Processing & Petrochemical Technology 2017年第3期19卷 1-8页

作者： Yu Jing Wang Jiming Key Laboratory of Advanced Control and Optimization for Chemical Process Ministry of EducationEast China University of Science and TechnologyShanghai 200237 DuPont China Holding Co. LtdShanghai 201203 School of Chemical Engineering East China University of Science and TechnologyShanghai 200237

Several metal terephthalates were synthesized by hydrothermal solvent method. Firstly, the coordination type of metal ions and carboxylates in terephthalate was studied by FTIR spectroscopy. The results showed that the binding type of zinc terephthalate and aluminum terephthalate are mainly bridged coordination, while the chelating coordination mode dominated in the magnesium terephthalate and cerium terephthalate. Secondly, the thermal decomposition mechanism of zinc terephthalate in nitrogen atmosphere was studied by tg and Py-GC/MS techniques. Finally, the activation energy of the thermal decomposition process was obtained by the Friedman method and the Flynn-Wall-Ozawa(FWO) method, and the most probabilistic function was obtained by multiple linear fitting. The results showed that the decomposition process of zinc terephthalate was an one-step reaction and the activation energy was equal to 187.38 kJ/mol.

关键词： terephthalate tg/dtg thermal decomposition mechanism kinetics

Preparation and characterization of ZnO nanometer powder

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中国有色金属学会会刊：英文版 2004年第1期14卷 198-201页

作者：吴振玉方正肖利徐洪耀 School of Chemistry and Chemical Engineer Central South University School of Chemistry and Chemical Engineer Anhui University Hefei 230039 China School of Chemistry and Chemical Engineer Anhui University

Hard zinc from thermo plating zinc factory had been treated for preparation of ZnO nano powder by chemical precipitation. The ion type and non ion type surface active reagents were added in different steps and ultrasonic agitation was used in preparing process. tg/dtg was applied to determine thermo decomposition temperature of the precursor as about 450 ℃. The product is light yellow, and had been characterized by XRD, S BET and TEM, through which the good dispersing sphere particles with the average diameter of approximately 5060 nm are observed, and the crystal is pure ZnO with hexahedral structure. The cost of preparing nanometer zinc oxide is low.

关键词：氧化锌纳米粉末制备性能 tg/dtg XRD TEM

Behavior and Kinetics of Non-isothermal Pyrolysis of Coal at Different Heating Rates

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China Petroleum Processing & Petrochemical Technology 2017年第3期19卷 89-96页

作者： Fan Junfeng Tian Bin An Xiaoxi Yin Mengmeng Qiao Yingyun Tian Yuanyu Key Laboratory of Low Carbon Energy and Chemical Engineering Shandong University of Science and Technology State Key Laboratory of Heavy Oil Processing China University of Petroleum

Investigations on the pyrolysis and kinetic behaviors during pyrolysis of fossil fuel samples, such as coal, are fundamental for developing the related technology and practical application. In this work, pyrolysis behavior and kinetics in the pyrolysis process of a coal sample were investigated by the thermogravimetric analyzer at a heating rate of 10, 40, 70,100, 200, and 500 °C/min, respectively. The pyrolysis process could be divided into four stages according to the tg/dtg curves. The first stage was mainly attributed to the removal of volatiles, and the second peak was the polycondensation reaction between the volatile components. It was found that more volatiles could be released from coal during pyrolysis at higher heating rate and the higher pyrolysis temperature was necessary for a rapid pyrolysis process. Kinetic analysis revealed that both the model-free(KAS and FWO) and the Coats-Redfern methods were suitable to describing the pyrolysis process, and the variation of activation energy(E) with the two types of kinetic models was consistent during the whole pyrolysis process. Furthermore, the heating rate did not alter the reaction sequence of the whole pyrolysis process, but higher heating rate could make the E value of the initial pyrolysis stage smaller.

关键词： pyrolysis behavior kinetic analysis tg/dtg curves activation energy

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广西靖西县新圩铝土矿Ⅶ号矿体矿石热分析

矿物岩石 2008年第4期28卷 53-58页

作者：刘学飞王庆飞张起钻周芳高帮飞徐浩中国地质大学地质过程与矿产资源国家重点实验室北京100083 中国地质大学岩石圈构造、深部过程及探测技术教育部重点实验室北京100083 广西省地质矿产局广西南宁530012

广西靖西新圩堆积型铝土矿为我国典型的一水铝型铝土矿。以新圩堆积型铝土矿的典型样品为研究对象,通过X衍射分析确定其矿物组成,进一步借助差热(DTA)与热重(tg/dtg)分析,探索铝土矿石加热过程。X衍射分析显示5个铝土矿样品矿物组成主... 详细信息

广西靖西新圩堆积型铝土矿为我国典型的一水铝型铝土矿。以新圩堆积型铝土矿的典型样品为研究对象,通过X衍射分析确定其矿物组成,进一步借助差热(DTA)与热重(tg/dtg)分析,探索铝土矿石加热过程。X衍射分析显示5个铝土矿样品矿物组成主要为硬水铝石、赤铁矿、绿泥石、三水铝石、锐钛矿、金红石、针铁矿以及少量的高岭石。差热(DTA)分析显示铝土矿样品有2个明显的吸热峰,分别为三水铝石和硬水铝石吸热峰;热重(tg/dtg)曲线显示样品分解分为4个阶段,分别为吸附水失去阶段和三水铝石、针铁矿、硬水铝石脱羟基作用阶段。利用热重(tg/dtg)数据分别计算了硬水铝石、三水铝石、针铁矿矿物相对百分含量,与国内外同类型铝土矿矿石热分析特征对比显示具有大体一致的热分析特征。

关键词：堆积型铝土矿喀斯特型铝土矿 XRD DTA tg/dtg

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烟酸锌热分解动力学研究

功能材料 2009年第5期40卷 817-819页

作者：孙秋香张克立黄元乔李彭袁良杰湖北第二师范学院化学系湖北武汉430205 武汉大学化学与分子科学学院湖北武汉430072

采用流变相反应法合成了烟酸锌配合物,用热分析(tg/dtg)、X射线衍射(XRD)技术研究了固态物质烟酸锌在空气中热分解的过程。热分析结果表明,烟酸锌在空气中是一步分解,其失重率与理论计算失重率相吻合。XRD结果表明,烟酸锌分解的终产物为... 详细信息

采用流变相反应法合成了烟酸锌配合物,用热分析(tg/dtg)、X射线衍射(XRD)技术研究了固态物质烟酸锌在空气中热分解的过程。热分析结果表明,烟酸锌在空气中是一步分解,其失重率与理论计算失重率相吻合。XRD结果表明,烟酸锌分解的终产物为ZnO。用Friedman法和Flynn-Wall-Ozawa(FWO)法求取了分解过程的活化能E,并用多元线性回归法给出了可能的机理函数,由这些方法得到的动力学数据相互比较吻合。

关键词：烟酸锌 tg/dtg XRD 热分解动力学